Java读取Properties的方式
项目结构:经典的maven项目结构
配置文件1和2内容一致:
jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=mysql://localhost:3306/database?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai
jdbc.username=root
jdbc.password=123456
1. this.getClass().getResourceAsStream()
//读取配置文件1
public void readProperties1() throws IOException {
//不加/会从当前包进行寻找,加上/会从src开始找
InputStream inputStream = this.getClass().getResourceAsStream("/jdbc.properties");
Properties properties=new Properties();
properties.load(inputStream);
System.out.println("jdbc.driver="+properties.getProperty("jdbc.driver"));
System.out.println("jdbc.url="+properties.getProperty("jdbc.url"));
System.out.println("jdbc.username="+properties.getProperty("jdbc.username"));
System.out.println("jdbc.password="+properties.getProperty("jdbc.password"));
}
//读取配置文件2
public void readProperties1() throws IOException {
InputStream inputStream = this.getClass().getResourceAsStream("/config/jdbc2.properties");
Properties properties=new Properties();
properties.load(inputStream);
System.out.println("jdbc.driver="+properties.getProperty("jdbc.driver"));
System.out.println("jdbc.url="+properties.getProperty("jdbc.url"));
System.out.println("jdbc.username="+properties.getProperty("jdbc.username"));
System.out.println("jdbc.password="+properties.getProperty("jdbc.password"));
}
2.当前类的加载器进行读取this.getClass().getClassLoader().getResourceAsStream()
//读取配置文件1
public void readProperties2() throws IOException {
//不加/,若加了会为null
InputStream inputStream = this.getClass().getClassLoader().getResourceAsStream("jdbc.properties");
Properties properties=new Properties();
properties.load(inputStream);
System.out.println("jdbc.driver="+properties.getProperty("jdbc.driver"));
System.out.println("jdbc.url="+properties.getProperty("jdbc.url"));
System.out.println("jdbc.username="+properties.getProperty("jdbc.username"));
System.out.println("jdbc.password="+properties.getProperty("jdbc.password"));
}
//读取配置文件2
public void readProperties2() throws IOException {
InputStream inputStream = this.getClass().getClassLoader().getResourceAsStream("config/jdbc2.properties");
Properties properties=new Properties();
properties.load(inputStream);
System.out.println("jdbc.driver="+properties.getProperty("jdbc.driver"));
System.out.println("jdbc.url="+properties.getProperty("jdbc.url"));
System.out.println("jdbc.username="+properties.getProperty("jdbc.username"));
System.out.println("jdbc.password="+properties.getProperty("jdbc.password"));
}
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方法1和2区别: (classpath即为target/classes 这个目录)
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Class.getResourceAsStream() 从当前类所在的位置开始查找配置文件位置。要找到jdbc.properties和jdbc2.properties必须加/从classpath下开始查找
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Class.getClassLoader().getResourceAsStream() 默认就从classpath路径下开始查找,加上/会报空指针文章来源:https://www.toymoban.com/news/detail-434555.html
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十分有必要知道java中类的加载过程!!!文章来源地址https://www.toymoban.com/news/detail-434555.html
3. ClassLoader类的static方法 getSystemResourceAsStream()
public void readProperties3() throws IOException {
//InputStream inputStream = ClassLoader.getSystemResourceAsStream("config/jdbc2.properties");
InputStream inputStream = ClassLoader.getSystemResourceAsStream("jdbc.properties");
Properties properties=new Properties();
properties.load(inputStream);
System.out.println("jdbc.driver="+properties.getProperty("jdbc.driver"));
System.out.println("jdbc.url="+properties.getProperty("jdbc.url"));
System.out.println("jdbc.username="+properties.getProperty("jdbc.username"));
System.out.println("jdbc.password="+properties.getProperty("jdbc.password"));
}
4. Spring中的 ClassPathResource读取
public void readProperties4() throws IOException {
//ClassPathResource resource = new ClassPathResource("jdbc.properties");
ClassPathResource resource = new ClassPathResource("config/jdbc2.properties");
Properties properties= PropertiesLoaderUtils.loadProperties(resource);
System.out.println("jdbc.driver="+properties.getProperty("jdbc.driver"));
System.out.println("jdbc.url="+properties.getProperty("jdbc.url"));
System.out.println("jdbc.username="+properties.getProperty("jdbc.username"));
System.out.println("jdbc.password="+properties.getProperty("jdbc.password"));
}
5. PropertyResourceBundle读取InputStream流
public void readProperties5() throws IOException {
//InputStream inputStream = ClassLoader.getSystemResourceAsStream("jdbc.properties");
InputStream inputStream = ClassLoader.getSystemResourceAsStream("config/jdbc2.properties");
PropertyResourceBundle bundle = new PropertyResourceBundle(inputStream);
System.out.println(bundle.getString("jdbc.driver"));
System.out.println(bundle.getString("jdbc.url"));
System.out.println(bundle.getString("jdbc.username"));
System.out.println(bundle.getString("jdbc.password"));
}
6.ResourceBundle.getBundle()
//不用输入后缀
public void readProperties6() {
//ResourceBundle bundle=ResourceBundle.getBundle("jdbc");
ResourceBundle bundle=ResourceBundle.getBundle("config/jdbc2");
System.out.println(bundle.getString("jdbc.driver"));
System.out.println(bundle.getString("jdbc.url"));
System.out.println(bundle.getString("jdbc.username"));
System.out.println(bundle.getString("jdbc.password"));
}
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